1. Field of the Invention
The invention is directed to a system that will determine the relative position of a beam mounted on the support and movable with respect to the support along an axis of movement, and additionally, or alternatively, will detect whether the beam is supported on the ground. In particular, the invention is directed to a system for use in connection with an apparatus, such as a crane, having telescoping outrigger beams and jacks for stabilizing the apparatus. In accordance with the invention, a system is provided that generates a first signal varying as the beam is moved along said axis to thereby provide a signal indicating the position of the beam with respect to the support. The system may further detect whether the outrigger jacks are lowered and supporting the crane.
2. Background of the Invention
Heavy construction equipment, such as a mobile crane, typically includes a carrier unit in the form of a transport chassis and a superstructure unit having an extendable boom. The superstructure unit is typically rotatable upon the carrier unit. In transport the crane is supported by the carrier unit on its axles and tires.
When used for lifting operations the crane should normally be stabilized to a greater degree than is possible while resting on the tires and axles of the transport chassis. In order to provide stability and support of the crane during lifting operations, it is well known to provide the carrier unit with an outrigger system. An outrigger system will normally include at least two (often four or more) telescoping outrigger beams with inverted jacks for supporting the crane when the crane is located in a position at which it will perform lifting tasks.
Utilizing the extensible beams, the jacks may be positioned at locations at which they will provide a stabilizing base for the crane. The inverted jacks are lowered into contact with the ground in order to support and stabilize the carrier unit and the superstructure unit. The jacks may be lowered sufficiently, if desired, so as to support the crane in a manner such that the tires are elevated above the ground.
Historically, a crane operator would determine the degree to which the outrigger beams should be extended to properly stabilize a crane, and visually inspect to determine if the jacks were lowered to a degree such that they were supporting and stabilizing the crane. It is useful, however, to be able to monitor the positions and conditions of the outrigger elements automatically and to provide an indication to the operator of the arrangement and condition of the outriggers. It would also be beneficial to be able to monitor the position and condition of the outriggers and to then provide appropriate signals of those conditions to a crane monitoring and control system.
In particular, it is desirable to be able to measure the length of an outrigger beam as it is extended and to provide signals indicative of the extended length and, thus, the location of the jacks to assist in operation of the crane. Additionally, it is desirable to be able to monitor and determine whether the inverted jacks are actually extended to a point where they are actually supporting the crane, and to provide appropriate signals to assist in operation of the crane.